allmargin

Syntax

Description

S = allmargin(sys) computes
the gain margin, phase margin, delay margin and the corresponding
crossover frequencies of the SISO open-loop model sys.
The allmargin command is applicable to any SISO
model, including models with delays.

The output S is a structure with the following
fields:

GMFrequency — All –180°
(modulo 360°) crossover frequencies in rad/TimeUnit,
where TimeUnit is the time units of the input dynamic
system, specified in the TimeUnit property
of sys.

GainMargin — Corresponding
gain margins, defined as 1/G, where G is
the gain at the –180° crossover frequency. Gain margins
are in absolute units.

PMFrequency — All 0 dB crossover
frequencies in rad/TimeUnit, where TimeUnit is
the time units of the input dynamic system, specified in the TimeUnit property of sys).

PhaseMargin — Corresponding
phase margins in degrees.

DMFrequency and DelayMargin —
Critical frequencies and the corresponding delay margins. Delay margins
are specified in the time units of the system for continuous-time
systems and multiples of the sample time for discrete-time systems.

Stable — 1 if the nominal
closed-loop system is stable, 0 otherwise.

Where stability cannot be assessed, Stable is
set to NaN. In general, stability cannot be assessed
for an frd system.

S = allmargin(mag,phase,w,ts) computes
the stability margins from the frequency response data mag, phase, w,
and the sampling time, ts. Provide magnitude values mag in
absolute units, and phase values phase in degrees.
You can provide the frequency vector w in any units; allmargin returns
frequencies in the same units. allmargin interpolates
between frequency points to approximate the true stability margins.